This invention relates to an apparatus for filing picture information which has a plurality of memory units for memorizing picture information and, more particularly, to an apparatus for filing picture information, which is free from the possibility of erroneously destroying memorized picture information.
Recently, a document filing apparatus has been developed as an energy-saving apparatus for handling a great number of documents. With such a document filing apparatus, picture information is read out by optically scanning the document. The picture information thus obtained is then filed in a memory together with a corresponding index code. The picture information thus filed can be read out, when desired, by searching for the corresponding index code. The read-out picture information can be recorded on a recording sheet (hard copy) in a recording unit.
Magnetic tape memory devices and optical disc memory devices are used as the memory for this document filing apparatus. In the case of magnetic tape memory, picture information is stored on a magnetic tape via a magnetic head. The picture information is obtained by optically scanning the surface of a document to be filed using a laser beam and photoelectrically converting the information thus read out.
In the case of an optical disc memory, picture information obtained by the aforementioned optical scanning process is stored on a disc by rotating the disc at a constant speed, projecting a laser beam onto the disc in accordance with the picture information, and then evaporating a metal layer on the disc surface to form a track-like arrangement of pits (oval holes). The disc consists of a glass disc on which the metal layer is formed.
The magnetic tape memory, which magnetically memorizes picture information, has an advantage in that rewriting of memorized picture information, for instance, for correction or revision, can be readily performed. However, a major disadvantage of this memory is that memorized picture information can be easily lost or changed by erroneous operation, which is undesirable from the standpoint of preserving information.
The optical disc memory, with which picture information is stored by the formation of pits, is superior in terms of reliably preserving picture information. However, with this memory it is impossible to perform rewriting, for instance correction or revision, of picture information once it has been memorized.